Spectrum of the Supernova Relic Neutrino Background and Metallicity Evolution of Galaxies
Ken'ichiro Nakazato, Eri Mochida, Yuu Niino, Hideyuki Suzuki
备注：
14 pages, 14 figures, accepted for publication in ApJ. The supernova relic neutrino data computed in this study are available at http://asphwww.ph.noda.tus.ac.jp/srn/
The spectrum of the supernova relic neutrino (SRN) background from past stellar collapses including black hole formation (failed supernovae) is calculated. The redshift dependence of the black hole formation rate is considered on the basis of the metallicity evolution of galaxies. Assuming the mass and metallicity ranges of failed supernova progenitors, their contribution to SRNs is quantitatively estimated for the first time. Using this model, the dependences of SRNs on the cosmic star formation rate density, shock revival time and equation of state are investigated. The shock revival time is introduced as a parameter that should depend on the still unknown explosion mechanism of core collapse supernovae. The dependence on equation of state is considered for failed supernovae, whose collapse dynamics and neutrino emission are certainly affected. It is found that the low-energy spectrum of SRNs is mainly determined by the cosmic star formation rate density. These low-energy events will be observed in the Super-Kamiokande experiment with gadolinium-loaded water.
The spectrum and event rate of supernova relic neutrinos are calculated taking into account the dependence on the time it takes for the shock wave in supernova cores to revive. The shock revival time should depend on the still unknown explosion mechanism of collapse-driven supernovae. The contribution of black-hole-forming failed supernovae is also considered. The total event rate is higher for models with a longer shock revival time and/or a failed-supernova contribution. The hardness of the spectrum does not strongly depend on the shock revival time, but the spectrum becomes hard owing to th…
The detection of supernova relic neutrinos could provide precious information on the evolution of the universe, the formation of stars, the mechanism of supernova bursts and the related neutrino physics. Many experiments, such as Kamland, Borexino, Sudbury Neutrino Observatory and Super-Kamiokande have conducted searches for the supernova relic neutrinos. However, no supernova relic neutrino signal has been observed until now. This paper reports the background study on the supernova relic neutrinos search for the future neutrino experiment in SuperK-Gd project. The expected event rate for vari…
Core collapse of massive stars leads to different fates for various physical factors, which gives different spectra of the emitted neutrinos. We focus on the supernova relic neutrinos (SRNs) as a probe to investigate the stellar collapse fate. We present the SRN fluxes and event rate spectra at a detector for three resultant states after stellar core collapse, the typical mass neutron star, the higher mass neutron star, or the failed supernova forming a black hole, based on different nuclear equations of state. Then possible SRN fluxes are formed as mixtures of the three components. We also sh…
We review the computation of and associated uncertainties in the current understanding of the relic neutrino background due to core-collapse supernovae, black hole formation and neutron-star merger events. We consider the current status of uncertainties due to the nuclear equation of state (EoS), the progenitor masses, the source supernova neutrino spectrum, the cosmological star formation rate, the stellar initial mass function, neutrino oscillations, and neutrino self-interactions. We summarize the current viability of future neutrino detectors to distinguish the nuclear EoS and the temperat…
In support of ongoing projects we have compiled a database of supernovae with host metallicities determined from spectroscopy in the Sloan Digital Sky Survey (SDSS) which we are providing as a catalog for the general use of the community. Here we provide metallicity values in the KK04 (Kobulnicky & Kewley 2004), T04 (Tremonti et al. 2004), and D16 (Dopita et al. 2016) diagnostics as well as a compilation of the relevant line fluxes to allow users to compute their own metallicities. The sample presented here has approximately 1700 objects with a metallicity in at least one diagnostic, with abou…
In this paper, transient high energy events and their hosts are discussed with focus on signatures of radio synchrotron emission. Outstanding questions range from the origin of the two phases of radio emission in supernovae to the formation of conical jets launched at relativistic velocities in active nuclei to the formation of radio hotspots in FR II sources to the formation of radio relics and halos in clusters of galaxies to the origin of the relativistic electron population and its energy spectrum which is responsible for the synchrotron emission to the composition of the radio synchrotron…
A small fraction of core collapse supernovae (SNe) show evidence that the outgoing blast wave has encountered a substantial mass ~ 1-10 M_sun of circumstellar matter (CSM) at radii ~100-1000 AU, much more than can nominally be explained by pre-explosion stellar winds. In extreme cases this interaction may power the most luminous, optically-energetic SNe yet discovered. Interpretations for the origin of the CSM have thus far centered on explosive eruptions from the star just ~ years to decades prior to the core collapse. Here we consider an alternative possibility that the inferred CSM is a rel…
We present measurements of the pseudo-equivalent width of the Fe II,$λ$5018 absorption feature in the spectra of 12 Type IIP supernovae (SNe II) in low luminosity ($M>-17$) dwarf host galaxies. The Fe II,$λ$5018 line has been suggested to be a useful diagnostic of the metallicity of the SN progenitor stars. The events in our sample were discovered photometrically by the Pan-STARRS Survey for Transients (PSST), and classified spectroscopically by us. Comparing our sample to 24 literature SNe II, we find that those in low luminosity hosts have significantly weaker Fe II features, with a probabil…
Observational evidence suggests that some very massive stars in the local Universe may die as pair-instability supernovae. We present 2D simulations of the pair-instability supernova of a non-zero metallicity star. We find that very little mixing occurs in this explosion because metals in the stellar envelope drive strong winds that strip the hydrogen envelope from the star prior to death. Consequently, a reverse shock cannot form and trigger fluid instabilities during the supernova. Only weak mixing driven by nuclear burning occurs in the earliest stages of the supernova, and it is too weak t…
Context: Stellar evolution theory suggests that the relationship between number ratios of supernova (SN) types and metallicity holds important clues as to the nature of the progenitor stars (mass, metallicity, rotation, binarity, etc). Aims: We investigate the metallicity dependence of number ratios of various SN types, using a large sample of SN along with information on their radial position in, and magnitude of, their host galaxy. Methods: We derive typical galaxian metallicities (using the well known metallicity-luminosity relation) and local metallicities, i.e. at the position of the SN; …
We examine how the small-scale ($<$\,kpc) variation of metallicity within a galaxy, which is found in nearby galaxies, affect the observational estimates of metallicity in the explosion sites of transient events such as core-collapse supernovae (CC SNe) and gamma-ray bursts (GRBs). Assuming the same luminosity, metallicity, and spatial distributions of \ion{H}{ii}\ regions (hereafter HIIRs) as observed in M31, we compute the apparent metallicities that we would obtain when the spectrum of a target region is blended with those of surrounding HIIRs within the length scale of typical spatial reso…
Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) are crucial for constraining the properties of their progenitor systems. Theoretical studies predicted that the UV spectra, which probe the outermost layers of a SN, should be sensitive to the metal content of the progenitor. Using the largest SN Ia UV (lambda<2900 A) spectroscopic sample obtained from Neil Gehrels Swift Observatory, we investigate the dependence of UV spectra on metallicity. For the first time, our results reveal a correlation (~2 sigma) between SN Ia UV flux and host-galaxy metallicities, with SNe in more metal-ric…
We consider the effect of a change in the rate of flux decline in the U band for type II-P supernovae (SNe IIP) as a function of metallicity $Z$. Based on this effect, we propose a new method to determine the photometric redshift from the SN IIP light curve in the U band. Using the STELLA code, we have constructed model light curves in different bands for different redshifts $z = 0.0, 0.1$, and $0.3$ as the metallicity in the models decreases from $Z \sim 10^{-3}$ to $\sim 10^{-6}$. The flux in the U band is shown to reach a plateau at the lowest metallicities. We consider the influence of oth…
The nature of core-collapse supernova (SN) explosions is yet incompletely understood. The present article revisits the scenario in which the release of latent heat due to a first-order phase transition, from normal nuclear matter to the quark-gluon plasma, liberates the necessary energy to explain observed SN explosions. Here, the role of the metallicity of the stellar progenitor is investigated, comparing a solar metallicity and a low-metallicity case, both having a zero-age main sequence (ZAMS) mass of 75 $M_\odot$. It is found that low-metallicity models belong exclusively to the failed SN …
The metallicity of a supernova (SN) progenitor, together with its mass, is one of the main parameters that rules their outcome. We present a metallicity study of 115 nearby SN host galaxies (0.005<z<0.03) which hosted 142 SNe using Integral Field Spectroscopy (IFS) from the CALIFA survey. Using O3N2 we found no statistically significant differences between the gas-phase metallicities at the locations of the three main SN types (Ia, Ib/c and II) all having ~8.50$\pm$0.02 dex. The total galaxy metallicities are also very similar and we argue that this is because our sample consists only of SNe d…
Type IIb supernovae are believed to originate from core-collapse progenitors having kept only a very thin hydrogen envelope. We aim to explore how some physical factors, such as rotation, metallicity, overshooting, and the initial orbital period in binaries, significantly affect the Roche lobe overflow and the formation of type IIb supernovae. It is found that binaries are the main channel that capable of producing type typeIIb supernovae progenitors in the mass range for initial masses below 20 $M_{\odot}$. The formation of type IIb supernova progenitors is extremely sensitive to the initial …
Red supergiants have been confirmed as the progenitor stars of the majority of hydrogen-rich type II supernovae. However, while such stars are observed with masses >25M$_\odot$, detections of >18M$_\odot$ progenitors remain elusive. Red supergiants are also expected to form at all metallicities, but discoveries of explosions from low-metallicity progenitors are scarce. Here, we report observations of the type II supernova, SN 2015bs, for which we infer a progenitor metallicity of $\leq$0.1Z$_\odot$ from comparison to photospheric-phase spectral models, and a Zero Age Main-Sequence mass of 17-2…
A survey of Type II supernovae explosion models has been carried out to determine how their light curves and spectra vary with their mass, metallicity, and explosion energy. The presupernova models are taken from a recent survey of massive stellar evolution at solar metallicity supplemented by new calculations at subsolar metallicity. Explosions are simulated by the motion of a piston near the edge of the iron core and the resulting light curves and spectra are calculated using full multi-wavelength radiation transport. Formulae are developed that describe approximately how the model observabl…
The ultimate understanding of Type Ia Supernovae diversity is one of the most urgent issues to exploit thermonuclear explosions of accreted White Dwarfs (WDs) as cosmological yardsticks. In particular, we investigate the impact of the progenitor system metallicity on the physical and chemical properties of the WD at the explosion epoch. We analyze the evolution of CO WDs through the accretion and simmering phases by using evolutionary models based on time-dependent convective mixing and an extended nuclear network including the most important electron captures, beta decays and URCA processes. …
Supernova (SN) feedback plays a vital role in the evolution of galaxies. While modern cosmological simulations capture the leading structures within galaxies, they struggle to provide sufficient resolution to study small-scale stellar feedback, such as the detailed evolution of SN remnants. It is thus common practice to assume subgrid models that are rarely extended to low metallicities, and which routinely use the standard solar abundance pattern. With the aid of 1-d hydrodynamical simulations, we extend these models to consider low metallicities and non-solar abundance patterns as derived fr…
Beyond-the-Standard-Model interactions of neutrinos among themselves -- {\it secret interactions} -- in the supernova core may prevent the shock revival, halting the supernova explosion. Besides, if supernova neutrinos en route to Earth undergo secret interactions with relic neutrinos, the neutrino burst reaching Earth may be down-scattered in energy, falling below the detection threshold. We probe secret neutrino interactions through supernova neutrinos and apply our findings to the supernova SN 1987A. We place the most stringent bounds on flavor-universal secret interactions occurring throug…
The neutrino process ($ν$-process) for the production of 7Li and 11B in core-collapse supernovae (SNe) is extensively investigated. Initial abundances of s-nuclei and other physical conditions are derived from an updated calculation of the SN 1987A progenitor. The nuclear reaction network including neutrino reactions is constructed with the variable order Bader-Deuflhard integration method. We find that yields of 7Li and 11B significantly depend on the stellar metallicity while they are independent of the weak s-process during the stellar evolution. When the metallicity is high, there are more…
In this fourth paper of the series, we use the parametrized, spherically symmetric explosion method PUSH to perform a systematic study of two sets of non-rotating stellar progenitor models. Our study includes pre-explosion models with metallicities Z=0 and Z=Z$_{\odot}\times 10^{-4}$ and covers a progenitor mass range from 11 up to 75 M$_\odot$. We present and discuss the explosion properties of all models and predict remnant (neutron star or black hole) mass distributions within this approach. We also perform systematic nucleosynthesis studies and predict detailed isotopic yields as function …
Superluminous supernovae (SLSNe) are found predominantly in dwarf galaxies, indicating that their progenitors have a low metallicity. However, the most nearby SLSN to date, SN 2017egm, occurred in the spiral galaxy NGC 3191, which has a relatively high stellar mass and correspondingly high metallicity. In this paper, we present detailed analysis of the nearby environment of SN 2017egm using MaNGA IFU data, which provides spectral data on kiloparsec scales. From the velocity map we find no evidence that SN 2017egm occurred within some intervening satellite galaxy, and at the SN position most me…
The physical process whereby a carbon--oxygen white dwarf explodes as a Type Ia supernova (SN Ia) remains highly uncertain. The degree of neutronization in SN Ia ejecta holds clues to this process because it depends on the mass and the metallicity of the stellar progenitor, and on the thermodynamic history prior to the explosion. We report on a new method to determine ejecta neutronization using Ca and S lines in the X-ray spectra of Type Ia supernova remnants (SNRs). Applying this method to \textit{Suzaku} data of Tycho, Kepler, 3C 397 and G337.2$-$0.7 in the Milky Way, and N103B in the Large…
Double detonations in sub-Chandrasekhar mass carbon-oxygen white dwarfs with helium shell are a potential explosion mechanism for a Type Ia supernova (SNe Ia). It comprises a shell detonation and subsequent core detonation. The focus of our study is on the effect of the progenitor metallicity on the nucleosynthetic yields. For this, we compute and analyse a set of eleven different models with varying core and shell masses at four different metallicities each. This results in a total of 44 models at metallicities between 0.01$Z_\odot$ and 3$Z_\odot$. Our models show a strong impact of the metal…
In Type Ia Supernovae (\sneia), the relative abundances of chemical elements are affected by the neutron excess in the composition of the progenitor white dwarf. Since these products leave signatures in the spectra near maximum light, spectral features may be used to constrain the composition of the progenitor. We calculate the nucleosynthetic yields for three \snia simulations, assuming single degenerate, Chandrasekhar mass progenitors, for a wide range of progenitor metallicities, and calculate synthetic light curves and spectra to explore correlations between progenitor metallicity and the …
The power of binaries on stripped-envelope supernovae across metallicity: uniform progenitor parameter space and persistently low ejecta masses, but subtype diversity
Type IIb supernovae (SNe) are important candidates to understand mechanisms that drive the stripping of stripped-envelope (SE) supernova (SN) progenitors. While binary interactions and their high incidence are generally cited to favor them as Type IIb SN progenitors, this idea has not been tested using models covering a broad parameter space. In this paper, we use non-rotating single- and binary-star models at solar and low metallicities spanning a wide parameter space in primary mass, mass ratio, orbital period, and mass transfer efficiencies. We find that our single- and binary-star models c…
We report on the results from our measurements of the interstellar medium (ISM) abundances for the elements O, Ne, Mg, Si, and Fe in the Large Magellanic Cloud (LMC). We used the archival Chandra data for sixteen supernova remnants (SNRs) in the LMC (0453--68.5, DEM L71, N23, 0519--69.0, N49B, N132D, N49, N206, 0534--69.9, DEM L238, N63A, Honeycomb, N157B, 0540--69.3, DEM L316B, and 0548--70.4). Our results represent LMC abundance measurements based on the modern Chandra data. We place tight constraints on our measured elemental abundances and find lower abundances than previous measurements b…
We explore the effects of the deflagration to detonation transition (DDT) density on the production of Ni-56 in thermonuclear supernova explosions (type Ia supernovae). Within the DDT paradigm, the transition density sets the amount of expansion during the deflagration phase of the explosion and therefore the amount of nuclear statistical equilibrium (NSE) material produced. We employ a theoretical framework for a well-controlled statistical study of two-dimensional simulations of thermonuclear supernovae with randomized initial conditions that can, with a particular choice of transition densi…
The effect of metallicity on the observed light of Type Ia supernovae (SNe Ia) could lead to systematic errors as the absolute magnitudes of local and distant SNe Ia are compared to measure luminosity distances and determine cosmological parameters. The UV light may be especially sensitive to metallicity, though different modeling methods disagree as to the magnitude, wavelength dependence, and even the sign of the effect. The outer density structure, ^56 Ni, and to a lesser degree asphericity, also impact the UV. We compute synthetic photometry of various metallicity-dependent models and comp…
The distribution of stars in the Hertzsprung Russell diagram (HRD) for a stellar conglomeration represents a snapshot of its evolving stellar population. Some of the supergiant stars may transit the HRD from blue to red and then again to blue during their late evolutionary stages, as exemplified by the progenitor of SN 1987A. Others may transit a given part of the HRD more than twice in a "blue loop" and end up as red supergiants before they explode. Since stars in blue loops spend a considerable part of their lives there, these stages may change the relative number of modeled supergiants in t…
We investigate the environment of the nearby (d ~ 40Mpc) broad-lined Type Ic supernova SN 2009bb. This event was observed to produce a relativistic outflow likely powered by a central accreting compact object. While such a phenomenon was previously observed only in long-duration gamma-ray bursts (LGRBs), no LGRB was detected in association with SN 2009bb. Using an optical spectrum of the SN 2009bb explosion site, we determine a variety of ISM properties for the host environment, including metallicity, young stellar population age, and star formation rate. We compare the SN explosion site prope…
We have performed deep X-ray observations of the remnant of Kepler's supernova (SN 1604) as a Key Project of the Suzaku Observatory. Our main goal is to detect secondary Fe-peak elements in the SN ejecta to gain insights into the Type Ia supernova explosion mechanism and the nature of the progenitor. Here we report our initial results. We made a conclusive detection of X-ray emission lines from highly ionized Mn, Cr, and Ni as well as Fe. The observed Mn-to-Cr line flux ratio is ~0.60, ~30% larger than that measured in Tycho's remnant. We estimate a Mn-to-Cr mass ratio of ~0.77, which is stron…
The mass distribution of neutron stars and stellar-mass black holes provides vital clues into the nature of stellar core collapse and the physical engine responsible for supernova explosions. Using recent advances in our understanding of supernova engines, we derive mass distributions of stellar compact remnants. We provide analytical prescriptions for compact object masses for major population synthesis codes. In an accompanying paper, Belczynski et al., we demonstrate that these qualitatively new results for compact objects can explain the observed gap in the remnant mass distribution betwee…
Even though the main nucleosynthetic products of type Ia supernovae belong to the iron-group, intermediate-mass alpha-nuclei (silicon, sulfur, argon, and calcium) stand out in their spectra up to several weeks past maximum brightness. Recent measurements of the abundances of calcium, argon, and sulfur in type Ia supernova remnants have been interpreted in terms of metallicity-dependent oxygen burning, in accordance with previous theoretical predictions. It is known that $α$-rich oxygen burning results from $^{16}$O$\rightarrow^{12}$C followed by efficient $^{12}$C+$^{12}$C fusion reaction, as …
We investigate a scenario in which feedback from black-hole X-ray binaries (BHXBs) sometimes begins inside young star clusters before strong supernova feedback. Those BHXBs could reduce the gas fraction inside embedded young clusters whilst maintaining virial equilibrium, which may help globular clusters (GCs) to stay bound when supernova-driven gas ejection subsequently occurs. Adopting a simple toy model with parameters guided by BHXB population models, we produce GC formation efficiencies consistent with empirically-inferred values. The metallicity dependence of BHXB formation could natural…
We present optical imaging and spectroscopy of supernova (SN) LSQ13fn, a type II supernova with several hitherto-unseen properties. Although it initially showed strong symmetric spectral emission features attributable to \ion{He}{ii}, \ion{N}{iii}, and \ion{C}{iii}, reminiscent of some interacting SNe, it transitioned into an object that would fall more naturally under a type II-Plateau (IIP) classification. However, its spectral evolution revealed several unusual properties: metal lines appeared later than expected, were weak, and some species were conspicuous by their absence. Furthermore, t…
We investigate explosive nucleosynthesis in a non-rotating 15$M_\odot$ star with solar metallicity that explodes by a neutrino-heating supernova (SN) mechanism aided by both standing accretion shock instability (SASI) and convection. To trigger explosions in our two-dimensional hydrodynamic simulations, we approximate the neutrino transport with a simple light-bulb scheme and systematically change the neutrino fluxes emitted from the protoneutron star. By a post-processing calculation, we evaluate abundances and masses of the SN ejecta for nuclei with the mass number $\le 70$ employing a large…
Pair Instability Supernovae have been suggested as candidates for some Super Luminous Supernovae, such as SN 2007bi, and as one of the dominant types of explosion occurring in the early Universe from massive, zero-metallicity Population III stars. The progenitors of such events can be rapidly rotating, therefore exhibiting different evolutionary properties due to the effects of rotationally-induced mixing and mass-loss. Proper identification of such events requires rigorous radiation hydrodynamics and radiative transfer calculations that capture not only the behavior of the light curve but als…
This paper presents a database of the spectroscopic- and photometric- spectral energy distributions (spec-SEDs and phot-SEDs) of the progenitors of core-collapse supernovae (CCSNe). Both binary- and single-star progenitors are included in the database. The database covers the initial metallicity ($Z$) range of 0.0001--0.03, mass range of 8--25 \dsm{}, binary mass ratio range of 0--1, and orbital period range of 0.1--10000\,days. The low-resolution spec-SEDs and phot-SEDs of single- and binary-star CCSN progenitors are included in the database. These data can be used for studying the basic para…
Evolution and final fate of solar metallicity stars in the mass range 7-15 Msun. I. The transition from AGB to SAGB stars, Electron Capture and Core Collapse Supernovae progenitors
Stripped-envelope stars can be observed as Wolf-Rayet (WR) stars, or as less luminous hydrogen-poor stars with low mass loss rates and transparent winds. Both types are potential progenitors of Type I core-collapse supernovae (SNe). We use grids of core-collapse models obtained from helium stars at different metallicities to study the effects of metallicity on the transients and remnants these stars produce. We characterise the surface and core properties of our core collapse models, and investigate their explodability employing three criteria. In cases where explosions are predicted, we estim…
We report, for the first time, the detection of the Mn-K$α$ line in the Type IIb supernova (SN IIb) remnant, Cassiopeia A. Manganese ($^{55}$Mn after decay of $^{55}$Co), a neutron-rich element, together with chromium ($^{52}$Cr after decay of $^{52}$Fe), is mainly synthesized at the explosive incomplete Si burning regime. Therefore, the Mn/Cr mass ratio with its neutron excess reflects the neutronization at the relevant burning layer during the explosion. Chandra's archival X-ray data of Cassiopeia A indicate a low Mn/Cr mass ratio with values in the range 0.10--0.66, which, when compared to …
Recent evidence has suggested that the supernova remnant (SNR) 0104-72.3 in the Small Magellanic Cloud (SMC) may be the result of a prompt Type Ia SN based on enhanced iron abundances and its association with a star-forming region. In this paper, we present evidence that SNR 0104-72.3 arose from a jet-driven bipolar core-collapse SN. Specifically, we use serendipitous Chandra X-ray Observatory data of SNR 0104-72.3 taken due to its proximity to the calibration source SNR E0102-72.3. We analyze 56 Advanced CCD Imaging Spectrometer (ACIS) observations of SNR 0104-72.3 to produce imaging and spec…
Relative frequencies of core-collapse supernovae as a function of metallicity: observations vs theoretical predictions
European Southern Observatory（欧洲南方天文台）；Institute of Astrophysics, Foundation for Research and Technology–Hellas（希腊研究基金会天体物理学研究所）；National and Kapodistrian University of Athens（雅典国立卡波迪斯特里阿斯大学）；Institut d’Astrophysique de Paris, CNRS-Sorbonne Université（巴黎天体物理学研究所，法国国家科学研究中心-索邦大学）；University of Turku（图尔库大学）；Institut d’Estudis Espacials de Catalunya (IEEC)（加泰罗尼亚空间研究院）；Institute of Space Sciences (ICE, CSIC)（空间科学研究所）
Stars in the mass range from 8 to 10 solar masses are expected to produce one of two types of supernovae (SNe), either electron-capture supernovae (ECSNe) or core-collapse supernovae (CCSNe), depending on their previous evolution. Either of the associated progenitors retain extended and massive hydrogen-rich envelopes, the observables of these SNe are, therefore, expected to be similar. In this study we explore the differences in these two types of SNe. Specifically, we investigate three different progenitor models: a solar-metallicity ECSN progenitor with an initial mass of 8.8 solar masses, …
We present an analysis of a new sample of type II core-collapse supernovae (SNe II) occurring within low-luminosity galaxies, comparing these with a sample of events in brighter hosts. Our analysis is performed comparing SN II spectral and photometric parameters and estimating the influence of metallicity (inferred from host luminosity differences) on SN II transient properties. We measure the SN absolute magnitude at maximum, the light-curve plateau duration, the optically thick duration, and the plateau decline rate in the V-band, together with expansion velocities and pseudo-equivalent-widt…
